Fixed a bug in the tokenizer to make sure it reverses the list before returning. Fixed up the calc engine, however addition/subtraction bugs still exist.

calc_engine.py

@@ -1,12 +1,11 @@
 import token
 
-def calculate_results(tokens):
-	
-	return 0
+def calculate_results(tokens):	
+	return handle_add_and_subtract(tokens)
 	
 def handle_parenthesis(tokens, call_has_priority = False):
 	running_value = 0
-	previous_token = CToken("", token.TokenType.unknown)
+	previous_token = token.CToken("", token.TokenType.unknown)
 	
 	while True:
 		if len(tokens) == 0:
@@ -38,7 +37,7 @@ def handle_parenthesis(tokens, call_has_priority = False):
 			if not previous_token.type == token.TokenType.unknown:
 				tokens.append(previous_token)
 			else:
-				tokens.append(CToken(running_value, token.TokenType.constant))
+				tokens.append(token.CToken(running_value, token.TokenType.constant))
 				
 			running_value = handle_add_and_subtract(tokens)
 			#Set the previous_token to an invalid state so its not used by mistake.
@@ -74,7 +73,7 @@ def handle_parenthesis(tokens, call_has_priority = False):
 			if not previous_token.type == token.TokenType.unknown:
 				tokens.append(previous_token)
 			else:
-				tokens.append(CToken(running_value, token.TokenType.constant))
+				tokens.append(token.CToken(running_value, token.TokenType.constant))
 				
 			running_value = handle_multiply_and_division(tokens)
 			#Set the previous_token to an invalid state so its not used by mistake.
@@ -86,7 +85,7 @@ def handle_parenthesis(tokens, call_has_priority = False):
 				tokens.pop()
 				running_value = operate(running_value, tokens.pop().value, token.TokenType.power)
 				
-			if !caller_has_priority and len(tokens) > 0 and (peek_list(tokens).type == token.TokenType.multiply or peek_list(tokens).type == token.TokenType.divide):
+			if not call_has_priority and len(tokens) > 0 and (peek_list(tokens).type == token.TokenType.multiply or peek_list(tokens).type == token.TokenType.divide):
 				operator = tokens.pop()
 				two_ahead = tokens.pop()
 				
@@ -101,7 +100,7 @@ def handle_parenthesis(tokens, call_has_priority = False):
 
 def handle_multiply_and_division(tokens):
 	running_value = 0
-	previous_token = CToken("", token.TokenType.unknown)
+	previous_token = token.CToken("", token.TokenType.unknown)
 	
 	while True:
 		if len(tokens) == 0:
@@ -148,9 +147,10 @@ def handle_multiply_and_division(tokens):
 	
 def handle_add_and_subtract(tokens):
 	running_value = 0
-	previous_token = CToken("", token.TokenType.unknown)
+	previous_token = token.CToken("", token.TokenType.unknown)
 	
 	while True:
+
 		if len(tokens) == 0:
 			break
 		
@@ -177,7 +177,9 @@ def handle_add_and_subtract(tokens):
 					running_value = operate(previous_token.value, tmp, current_token.type)
 				else:
 					running_value = operate(running_value, tmp, current_token.type)
+					
 				previous_token.type = token.TokenType.unknown
+				continue
 			
 			if len(tokens) > 0:
 				two_ahead = peek_list(tokens)
@@ -206,7 +208,7 @@ def handle_add_and_subtract(tokens):
 			if previous_token.type != token.TokenType.unknown:
 				tokens.append(previous_token)
 			else:
-				tokens.append(CToken(running_value, token.TokenType.constant))
+				tokens.append(token.CToken(running_value, token.TokenType.constant))
 			
 			running_value = handle_multiply_and_division(tokens)
 			
@@ -222,15 +224,23 @@ def peek_list(tokens):
         raise IndexError("The token list is empty.", tokens)
 
 def operate(n1, n2, tokenType):
+	n1 = float(n1)
+	n2 = float(n2)
+	
 	if tokenType == token.TokenType.add:
-		print("Adding %d and %d to get %d." %(n1, n2, n1 + n2))
+		print("Adding %d and %d to get %d." %(n1, n2, n1 + n2))	
+		return n1 + n2
 	elif tokenType == token.TokenType.subtract:
 		print("Subtracting %d and %d to get %d." %(n1, n2, n1 - n2))
+		return n1 - n2
 	elif tokenType == token.TokenType.multiply:
-		print("Multiplying %d and %d to get %d" %(n1, n2, n1 * n2))
+		print("Multiplying %d and %d to get %d" %(n1, n2, n1 * n2))	
+		return n1 * n2
 	elif tokenType == token.TokenType.divide:
-		print("Dividing %d and %d to get %d" %(n1, n2, n1 / n2))
+		print("Dividing %d and %d to get %d" %(n1, n2, n1 / n2))	
+		return n1 / n2
 	elif tokenType == token.TokenType.power:
 		print("Raising %d to the power of %d to get %d" %(n1, n2, n1**n2))
+		return n1 ** n2
 	else:
 		raise TypeError("Invalid operator value " + str(tokenType) + ".", tokenType)

main.py

@@ -1,8 +1,12 @@
 import token
 import tokenizer
-#userInput = input('Enter your formula: ')
-tokens = tokenizer.get_tokens_from_expression_string("i + 2 / i (3 * n) 5")
+import calc_engine
 
-for t in tokens:
-	print("%s (%s) " %(t.value, token.TokenType.get_operator_name(t.type)), end = "")
-print()
+userInput = input('Enter your formula: ')
+tokens = tokenizer.get_tokens_from_expression_string(userInput)
+results = calc_engine.calculate_results(tokens)
+print(results)
+
+#for t in tokens:
+#	print("%s (%s) " %(t.value, token.TokenType.get_operator_name(t.type)), end = "")
+#print()

tokenizer.py

@@ -69,6 +69,10 @@ def get_tokens_from_expression_string(expression_string):
 			tokens.append(token.CToken(c + str(symbols_dic[c]), token.TokenType.variable))
 			parsing_number = False
 			tmp = ""
-
+	#When building this list we've effectively ordered the tokens in reverse order from how we want to
+	#process them. So, reverse the order of the list before returning them to the caller, we don't want
+	#the caller to have to worry about such a minor detail.
+	tokens.reverse()
+	
 	return tokens